docs: def get_attachments_ids(self, ticket_id):
          """ Get IDs of attachments for given ticket.
  
          :param ticket_id: ID of ticket
          :returns: List of IDs (type int) of attachments belonging to given
                    ticket. Returns None if ticket does not exist.
          """
          attachments = self.get_attachments(ticket_id)
          return [int(at[0]) for at in attachments] if attachments else attachments